My co-worker is jealous of my time off to fly to Trauma Center for Mom. I was gone last Mon/Tue/Wens and it was our 3rd trip out of town to the Trauma Hospital. They called me while we were at the hospital doing X-rays and follow-up appt. with the orthopedic surgeon. The call was about a routine task and was not an emergency. I couldn't believe my ears. My boss probably doesn't know that they called me.
But make him/her feel as though you really thought the call was helpful. Then he/she might not do it again, if in fact "checking up on you" was the motive.
Add that you are concerned the person who called you might feel that you're taking advantage of the situation, not keeping up with your work (whatever you think might be behind the call), and reassure your boss that you're still committed to doing everything you're responsible for.